Real-Time Monitoring of Interactions between Solid-Supported Lipid Vesicle Layers and Short- and Medium-Chain Length Alcohols: Ethanol and 1-Pentanol.

Shova Neupane,George Cordoyiannis,Patricia Losada-Pérez,Frank Uwe Renner

doi:10.3390/biomimetics4010008

Abstract

Lipid bilayers represent the interface between the cell and its environment, serving as model systems for the study of various biological processes. For instance, the addition of small molecules such as alcohols is a well-known process that modulates lipid bilayer properties, being considered as a reference for general anesthetic molecules. A plethora of experimental and simulation studies have focused on alcohol’s effect on lipid bilayers. Nevertheless, most studies have focused on lipid membranes formed in the presence of alcohols, while the effect of n-alcohols on preformed lipid membranes has received much less research interest. Here, we monitor the real-time interaction of short-chain alcohols with solid-supported vesicles of dipalmitoylphosphatidylcholine (DPPC) using quartz crystal microbalance with dissipation monitoring (QCM-D) as a label-free method. Results indicate that the addition of ethanol at different concentrations induces changes in the bilayer organization but preserves the stability of the supported vesicle layer. In turn, the addition of 1-pentanol induces not only changes in the bilayer organization, but also promotes vesicle rupture and inhomogeneous lipid layers at very high concentrations.

Highlights

The effect of small foreign molecules as model systems in lipid membranes is relevant to a broad range of biochemical and medical processes where membrane–molecules complexes are involved, namely passive transport through biomembranes, the effect of drugs, and the use of lipid membranes as carriers
We examined the interactions of supported vesicle layers (SVLs) of dipalmitoylphosphatidylcholine (DPPC) lipid preformed in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer with aqueous solutions of alcohols of different length, namely short-chain ethanol and medium-chain length 1-pentanol at the same concentrations
A suspension of Small unilamellar vesicles (SUVs) was injected at 16 C, with DPPC lipids being in the gel phase

Summary

Introduction

The effect of small foreign molecules as model systems in lipid membranes is relevant to a broad range of biochemical and medical processes where membrane–molecules complexes are involved, namely passive transport through biomembranes, the effect of drugs, and the use of lipid membranes as carriers. Some examples of small foreign molecules include cholesterol, fatty acids, and alcohols, systems that partition differently between the membrane phases and the aqueous environment. The latter have attracted a great deal of attention since they display a wide spectrum of physiological and pharmacological actions such as metabolism, membrane fusion, alcohol toxicity, and general anesthesia [1,2,3,4,5]. Alcohol-induced changes in lipid bilayer properties have been extensively studied for a variety of mechanical and thermodynamic properties to shed light on structure–property–function relationships. Examples range from membrane area expansion and decreased bending modulus [6], to changes in molar volumes [7], or channel ionic permeability [8]

Methods

Results

Conclusion